Two teenage boys have drowned in Perth's Swan River and there are fears for a third boy who's still missing after four teenagers jumped into the water to evade police.
The foot chase began mid-afternoon yesterday when officers responded to reports of five teenagers jumping fences in Maylands.
Police Commissioner Chris Dawson said four boys were seen jumping into the water.
Two were spotted struggling in very deep and murky water in the middle of the river and officers swam out in a rescue attempt but were unable to reach them before they went under.
"Police did not physically come into contact with the two boys who disappeared under water in the middle of the river," Mr Dawson told reporters.
Police divers found the first body in low visibility - estimated at 10cm in front of their face - just before 9pm.
The second body was recovered about 10am today.
"This is nothing short of a tragedy," Mr Dawson said. "The loss of any young life is an absolute tragedy."
Two other boys were captured, treated by paramedics and given dry clothes, then taken into custody and reunited with their families.
Mr Dawson said there were concerns for the fifth boy, who was last seen running along the riverbank and it's feared he may also have gone into the water.
He described the search for him as urgent. The two survivors have not been charged with any offences at this stage.
Mr Dawson urged the missing boy's family and associates to advise police of his welfare and not worry about him potentially being in trouble.
"We just want to know if he's safe," he said. "Any matters concerning offending need to be put squarely to one side.
"We are hopeful that he did not enter the river."
The commissioner said the deaths would be subject to an inquest and called on members of the public to provide any information or CCTV footage that may aid the investigation.
All of the boys were under 18 and police declined to release more details at the request of their families.